A fuel cell vehicle is a vehicle which is driven by a fuel cell that converts chemical energy into electric energy by a reaction of oxygen and hydrogen. As the fuel cell used in the fuel cell vehicle, a polymer electrolyte membrane fuel cell has been typically used.
When the polymer electrolyte membrane is adequately dipped into water, ion conductivity of the polymer electrolyte membrane is increased, and as consequence, a loss by resistance is reduced. When relative humidity of air and hydrogen which are supplied to the polymer electrolyte membrane is substantially, moisture of the polymer electrolyte membrane is reduced and the ion conductivity of the polymer electrolyte membrane is reduced, and as consequence, the loss by resistance increases. Meanwhile, when reaction gas having substantially reduced humidity is continuously supplied, the electrolyte membrane is dried after all and thus may not be used as the electrolyte membrane at all. As such, in the polymer electrolyte membrane fuel cells, the supplied gas needs to be humidified.
Accordingly, various methods for humidifying a fuel cell for a vehicle have been developed, and as a currently used device for humidifying the fuel cell for the vehicle, a gas-gas membrane humidification device has been widely used.
The gas to gas membrane humidification device is based on a method for making fuel cell exhaust gas flow in a first surface thereof and gas flow in a second surface with a membrane through which only moisture may penetrate the membrane. In particular, the supplied gas is discharged from a stack and simultaneously receives heat and water from the exhaust gas of which the temperature is elevated and the moisture is saturated.
However, the gas to gas membrane humidification device may also be expensive due to high manufacturing cost of an exchange membrane. Further, the gas to gas membrane humidification device may not have sufficient humidification performance and may not perform sufficient humidification in a high load area, and as a result, a vehicle may stop on an uphill road.
Meanwhile, in the conventional membrane humidification device for humidifying the fuel cell, humidification amount may not be controlled optimally. In the related arts, injector type humidification may be generally used for controlling the humidification amount.
The injector type humidification refers to injecting water by the injector to atomize the water such that a surface area may increase for evaporating the water, thereby improving humidification effect.
The humidification using the injector may have advantages. For example, the humidification amount may be easily controlled, injector humidification technologies which have been applied and researched in other technical fields may be applied, cost of the device may be less, and the like.
In the related arts, as an example of the existing injector type humidification technology, a gas humidification device and a method for operating a fuel cell system have been developed. The device includes a water pump pumping water from an external supply source, an air compressor compressing external air, and a mixing chamber and a magnetic type injection nozzle for mixing and injecting the compressed air and the water.
However, the fuel cell system also includes several components such as the compressor, the mixing chamber, and the like in addition to the water pump, and when an additional device is installed, costs may increase and a mounting area may increase in volume. Further, since moving part components such water pump, injection nozzle, and the like in which water flow are exposed to the outside as they are, the water may be easily frozen or leaked in cold temperature conditions.
In another example from the related arts, a water supply device for a fuel cell has been provided. When a proper amount of water is pumped by a water pump, and at the same time, injected into an inlet of a screw compressor by a magnetic nozzle, the injected water may be compressed along with air, cooled by an after-cooler, and then supplied to the fuel cell in the water supply device.
However, as described above, since the moving part components such as water pump, magnetic nozzle, and the like in which water flows are also exposed to the outside as they are, the water may be easily frozen or leaked in the cold weather condition.
The above information disclosed in this Background section is only for enhancement of understanding of the background of the invention and therefore it may contain information that does not form the prior art that is already known in this country to a person of ordinary skill in the art.